On Thu, 23 Jul 2015 13:33:36 -0400
Jason Baron <jasonbar...@gmail.com> wrote:
> On 07/23/2015 01:08 PM, Peter Zijlstra wrote:
> > On Thu, Jul 23, 2015 at 11:34:50AM -0400, Steven Rostedt wrote:
> >> On Thu, 23 Jul 2015 12:42:15 +0200
> >> Peter Zijlstra <pet...@infradead.org> wrote:
> >>
> >>> static __always_inline bool arch_static_branch_jump(struct static_key
> >>> *key, bool inv)
> >>> {
> >>> if (!inv) {
> >>> asm_volatile_goto("1:"
> >>> "jmp %l[l_yes]\n\t"
> >> And what happens when this gets converted to a two byte jump?
> >>
> > That would be bad, how can we force it to emit 5 bytes?
> hmm....I don't think that's an issue, the patching code can
> detect if its a 2-byte jump - 0xeb, or 5-byte: 0xe9, and do
> the correct no-op. Same going the other way. See the code
> I posted a few mails back. In fact, this gets us to the
> smaller 2-byte no-ops in cases where we are initialized
> to jump.
>
Ah right, and I already have the code that checks that (from the
original plan).
-- Steve
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